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To use LVM, partitions and whole disks must first be converted into physical volumes (PVs) using the pvcreate command. For example, to convert /dev/hda and /dev/hdb into PVs use the following commands :

# pvcreate /dev/hda

# pvcreate /dev/hdb

If a Linux partition is to be converted make sure that it is given partition type 0x8E using fdisk, then use pvcreate :

To be able to support failover connections to a device one needs multiple paths to that device. If we have a iSCSI disk connected to an ethernet network and we want to make sure that we can reach the disk from a host even when we disconnect one ethernet cable we need two network cables running from the host to the disk and we need a piece of software that makes sure when one link failes the other one is used. This last piece of software is called multipath on GNU/Linux systems.

To use ext4 file system, you need to have RedHat v5.3 or later, It means boot into 2.6.18-128.el5 or higher, and need a package.

# yum install e4fsprogs

The e4fsprogs package is designed to install alongside stock e2fsprogs without overlapping, so some utilities are renamed; for example e4fsck, debuge4fs, e4image, etc. rpm -q e4fsprogs | grep bin will give a good summary of what is included.

The ' dd ' command is one of the original Unix utilities and should be in everyone's tool box. It can strip headers, extract parts of binary files and write into the middle of floppy disks; it is used by the Linux kernel Makefiles to make boot images. It can be used to copy and convert magnetic tape formats, convert between ASCII and EBCDIC, swap bytes, and force to upper and lowercase.